<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>回文数</title>
</head>

<body>
  <script>
    let str = 121;
    str = String(str)
    let newStr = str.split("").reverse().join("");
    console.log(newStr === str)
  </script>
</body>

</html>